The present invention relates to a film product for the packaging products in sealed film packages, a method for preparing a film product, and a film package with a packaging that is at least partially filled with a product.
In general, it is known that film products are used to store and transport products, particularly liquids, in sealed foil packaging. In this context, frequent use is made of “FFS machines” (Form, Fill, Seal). The most frequently used products are continuous tubing or film webs that can be filled in a shared fill and seal process with general cargo or liquids. Such film packages are often consumer packaging, so that for example detergent or the like can be packaged in such a film package. Particularly in liquid packaging, such film packages are also called “pouches.” In order to manufacture such film packaging products in FFS machines, sealing jaws are required, which together seal the film product, especially individual film layers to produce a sealed seam. This sealed seam encloses a storage space inside the film packaging in substantially liquid-tight manner. The sealing jaws are heated to a sealing temperature until a part of the film product fuses or melts. For this purpose, a certain period of contact is needed between the sealing jaws and the film product so that sufficient quantities of heat can be exchanged.
With known devices, care must be taken to ensure that the sealing process does not contaminate the sealing jaws. To guarantee this, either the work is done at relatively low sealing temperatures or the sealing jaws are temporarily covered with Teflon tape. Consequently, either the Teflon strips have to be replaced after certain intervals, or the low sealing temperatures result in relatively long cycle times for creating the seal. In both cases, the productivity of such machines is reduced.
It is already known that “asymmetric film products” are used to provide a heat-sealable film layer and a thermally stable film layer together in as single film product. In the known film products, these two layers are produced together by a laminating process. The disadvantage of this is that both film layers have to be produced separately and then undergo a laminating process. This increases the cost of such asymmetric films significantly, so that they are only rarely used to produce film products for FFS machines. It is also known that coextrusion blow moulding machines that make different film layers in the coextrusion process are also used to produce tubular bags. A general capability of an extrusion blow moulding process is known from DE 10 2009 046 539 A1. Similarly, coextrusion blow moulding can also be performed. The document discloses a “dry coextrusion step”, wherein air cooling is provided from the outside and the inside for the extruded tubular film. However, a disadvantage of this coextrusion blow moulding process is that in asymmetric film layer compounds with different melting points, a tendency to roll up occurs, known as the “curl effect”. Cooling after leaving the nozzle creates thermally induced stresses in the film product material, which produce a tendency to curl in the film product. Film compounds consisting of different film layers that are produced in this way have only limited use, because they have disadvantages in terms of transparency and surface constitution. This curl effect or tendency to roll also means that they can only be used in FFS machines to a limited degree and/or only at low cycle speeds.